Apparatus and method of installing an alarm sensor to a corner wall

ABSTRACT

A security alarm sensor for mounting between two corner walls is described comprising a housing unit having a housing base for attachment to the corner walls and a selectively detachable housing cover; a circuit board sized for engagement within the housing unit; first and second openings on opposite sides of the housing base; first and second mounting pins selectively movable within the first and second openings wherein said mounting pins have a length and a range of movement so as to have a first position wherein the mounting pins are totally retracted within the housing unit and a second position wherein said mounting pins extend outwardly from the housing unit sufficiently to pierce the corner walls and securely hold the security alarm sensor in place. The installation of the alarm sensor is usually accomplished by first removing the housing cover from the housing base and detaching the printed circuit board prior to mounting the housing base to the corner of the wall.

FIELD OF THE INVENTION

[0001] This invention is generally directed to an apparatus and methodfor mounting security alarm sensors within a protected premises. Morespecifically, the apparatus and method of the present invention providesa means for easily connecting a security alarm sensor in a corner of aroom with minimal risk to the circuitry and without utilizing anyscrews, nails or mounting brackets.

BACKGROUND OF THE INVENTION

[0002] Burglaries, and the perceived risk thereof, have continuallyincreased, particularly in crowded urban areas. Thus, an increasingnumber of businesses and homes are protected by alarm systems. Mostalarm systems comprise an alarm control panel; a series of detectors,sensors and/or door/perimeter contacts; and a user-controlled keypad.Most sensors/detectors are strategically placed within a protectedpremises by a skilled installer so as to maximize the detection ofunauthorized intruders while minimizing the risk of false alarms causedby heaters, open windows, pets, etc. Various sensors/detectors existwhich can detect the motion or heat caused by an unauthorized intruderwhen the alarm system is armed. Examples of such sensors/detectorsinclude passive infrared (PIR) sensors, microwave sensors, ultrasonicdevices, etc. Many conventional sensors utilize dual technology deviceswhich combine complementary technologies to minimize false alarms.

[0003] The most effective and least unsightly position for many sensorsis in the corner of a room. However, it is often difficult for aninstaller to securely fasten the sensor in the corner of a room withouteither utilizing a corner mounting bracket or preventing damage to thehousing base or alarm circuitry when awkwardly connecting screws throughstandard corner mount screw holes. If precise placement of thesensor/detector is not made, its proper functioning is greatlyjeopardized.

[0004] Most conventional security alarm sensors are packaged as anintegrated housing unit. This housing unit includes a selectivelyattached housing base and housing cover with a printed circuit boardcontained therein. The installer will typically remove the housing coverfrom the housing base to expose the printed circuit board containedtherein. Next, the installer will carefully remove the printed circuitboard from the housing base to prepare the housing base for installationto a wall. The printed circuit board is removed to minimize the risk oftools damaging the circuitry thereof. The housing base is eithersecurely fastened in a corner of a room by means of a mounting bracketor by screws inserted through standard corner mount screw holes. Ineither case, mounting is typically slow and awkward due to thedifficulty of inserting screws at an angle while on a ladder. Obviously,in order to securely fasten the housing base to the wall, at least two,and preferably four, corner mounting screws must be used. Once thehousing base is in place, the installer will reinsert the printedcircuit board and reattach the housing cover.

[0005] Whenever screws are utilized by an installer, particularly whenon a ladder, they are often dropped, lost, etc. requiring evenadditional installation time and inconvenience for the installer. Thus,labor costs for installation companies are high. Thus, what is lackingin the prior art is a housing unit and method which permits cornermounting without the need for utilizing a corner mounting bracket or anyscrews whatsoever. Whether mounting brackets or screws are utilized, ifthe installer needs to reposition the sensor for any reason, the wallswill now contain damage due to screw holes. Thus, repair plasteringsometimes is warranted. This further increases the costs to installationcompanies.

[0006] It is therefore a primary object of the present invention toprovide a new and improved method and apparatus for mounting a securityalarm sensor to the corner of a wall.

[0007] It is another object of the present invention to provide a newand improved method and apparatus for mounting a security alarm sensorto the corner of a wall without utilizing mounting brackets or screws.

[0008] It is yet a further object of the present invention to provide anew and improved method and apparatus for mounting a security alarmsensor to the corner of a wall that, can be easily repositioned withoutcreating any unsightly holes on the walls.

[0009] Other objects and advantages of the present invention will becomeapparent from the specification and the drawings.

SUMMARY OF THE INVENTION

[0010] Briefly stated and in accordance with the preferred embodiment ofthe present invention, a security alarm sensor for mounting between twocorner walls is described comprising a housing unit having a housingbase for attachment to the corner walls and a selectively detachablehousing cover; a circuit board sized for engagement within the housingunit; first and second openings on opposite sides of the housing base;first and second mounting pins selectively movable within the first andsecond openings wherein said mounting pins have a length and a range ofmovement so as to have a first position wherein the mounting pins aretotally retracted within the housing unit and a second position whereinsaid mounting pins extend outwardly from the housing unit sufficientlyto pierce the corner walls and securely hold the security alarm sensorin place. The installation of the security alarm sensor is usuallyaccomplished by first removing the housing cover from the housing baseand detaching the printed circuit board prior to mounting the housingbase to the corner of the wall.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] While the specification concludes with claims particularlypointing out and distinctly claiming the subject matter regarded as theinvention herein, it is believed that the present invention will be morereadily understood upon consideration of the description, taken inconjunction with the accompanying drawings, wherein:

[0012]FIG. 1 is an exploded view of an alarm sensor in accordance withthe present invention which includes a housing unit comprising a housingbase and a housing cover, a printed circuit board, and a rotatablemounting disc;

[0013]FIG. 2 is a schematic illustration of the housing base and therotatable mounting disc in accordance with the present invention;

[0014]FIG. 3 is a schematic illustration of the housing base of thepresent invention being installed between two corner walls;

[0015]FIG. 4 is a schematic illustration of the back of the housing baseof the housing base and rotatable mounting disc in accordance with thepresent invention wherein mounting pins are in their retractableposition;

[0016]FIG. 5 is a schematic illustration of the back of the housing baseof the housing base and rotatable mounting disc in accordance with thepresent invention wherein mounting pins are in their extended position;

[0017]FIG. 6 is a cross-sectional view of FIG. 5 taken along referenceline 6-6.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018] Referring first to FIG. 1, an alarm sensor in accordance with thepresent invention is generally designated by reference numeral 10 andshown in exploded form. A housing unit comprised of a housing base 12and a housing cover 14 is shown. Within housing base 12 and housingcover 14 is a printed circuit board 16 and a rotatable mounting disc 18.Although shown as coupled to mounting disc 18, a first mounting pin 20and a second mounting pin 22 are typically separate from mounting disc18 and extend outwardly in generally opposite directions.

[0019] Printed circuit board 16 is shown as a PIR sensor forillustrative purposes. Thus, printed circuit board 16 includes a PIRsensor element 24 and a PIR lens 26. Also on printed circuit board 16are terminal strips 28 and 30. Terminal strips 28 and 30 are preferablycomprised of “speaker-jack style” terminals which simply snap down tosecure connecting wires. Thus, no terminal screws are necessary. In theinstance where alarm sensor 10 is a PIR sensor, housing cover 14 canalso be split in two components to allow for dual focal lengths for thePIR zones. Dual focal lengths are often incorporated in PIR sensors toeliminate false alarms due to pets. It will be noted by those skilled inthe art that the mounting apparatus and method of the present inventioncan be utilized not only for PIR sensors, but also for various securityalarm sensors based on microwave technology, ultrasound technology, orany variations thereof. Furthermore, the mounting apparatus and methodof the present invention is equally applicable to alarm sensors forfire, smoke, temperature, etc. Additionally, the mounting apparatus andmethod of the present invention can be utilized on hardwired or wirelesssensors. Thus, the actual components shown on printed circuit board 16are only illustrative; countless variations are possible.

[0020] Housing base 12 includes corner mount screw hole punch-outs 32,34, 36 and 38. An installer can selectively utilize screws throughcorner mount screw holes punch-outs 32, 34, 36 and 38 to mount housingbase 12 onto corner walls 40 and 42. Similarly, housing base 12illustrates four flat wall mount screw hole punch-outs 44, 46, 48 and50. An installer will selectively utilize flat wall mount screw holepunch-outs 44, 46, 48 and 50 when the housing base is to be installedonto a flat wall. Finally, housing base 12 also includes a swivel mountpunch-out 52 that allows installation so that alarm sensor 10 can bemade to slightly rotate. While the alternative utilization of cornermount screw hole punch-outs 32, 34, 36 and 38; flat wall mount screwhole punch-outs 44, 46, 48 and 50; or swivel mount punch-out 52 allows asingle housing unit to be incorporated in various applications, ascrewdriver is required for all installations. Particularly when acorner mounting is desired, the use of screws and a screwdriver on aladder is often burdensome.

[0021] Housing base 12 is adapted to receive rotatable mounting disc 18,first mounting pin 20, and second mounting pin 22. More specifically,housing base 12 includes a first guided groove 54, a second guidedgroove 56, a first guide slot 58 and a second guide slot 60. As bestshown in FIG. 2, first guide slot 58 permits a path upon which firstmounting pin 20 can easily travel whereas second guide slot 60 permits apath upon which second mounting pin 22 can easily travel. Based on theproper manipulation of rotatable mounting disc 18 by means of ascrewdriver slot 62, first mounting pin 20 can be made to either retractwithin or extend beyond a first opening 64 on housing base 12.Similarly, second mounting pin 22 can be made to either retract withinor extend beyond a second opening 66 on housing base 12. First opening64 and second opening 66 are typically on respective planes 65 and 67 ofhousing base 12 which are contoured at approximately 45° angles. Thisangle permits planes 65 and 67 to rest flatly on corner walls 40 and 42that generally form a 90° angle. This flush alignment is best seen inFIG. 3.

[0022] Before addressing the interconnection between rotatable mountingdisc 18 and housing base 12, and the manipulation of mounting disc 18 tocontrol the selective movement of first mounting pin 20 and secondmounting pin 22, it should be understood that alarm sensor 10 istypically packaged as a interconnected unit. Housing base 12 is snappedtogether to housing cover 14 with circuit board 16 and mounting disc 18therein. In order to separate housing base 12 from housing cover 14, ascrewdriver is typically inserted into a slot 68 to release a mountingtab (not shown) that holds housing unit 12 and housing base 14 together.At this stage, printed circuit board 16 is coupled to housing base 12 bymeans of a circuit board height index tab 70. When slight pressure isapplied to circuit board height index tab 70, circuit board 16 can beeasily removed. Circuit board 16 can be wired at this point so that whenultimately replaced within housing base 14, the wires can be easilydisplaced through the housing unit by means of a wire entry punch-out72. Obviously, wireless sensors would not require wire entry punch-out72.

[0023] Once housing base 12 and housing cover 14 have been separated andcircuit board 16 has been removed, housing base 12 is ready for mountingto walls 40 and 42. An installer will simply hold housing base 12 at adesired location, insert a screwdriver into screwdriver slot 62 and turnrotatable mounting disc 18 approximately 45°. The rotational movement ofmounting disc 18 will result in first mounting pin 20 and secondmounting pin 22 simultaneously moving outwardly so as to sufficientlypierce walls 40 and 42 and secure housing base 12 in place. At thispoint, printed circuit board 16 would be reconnected to housing base 12by manipulating circuit board index tab 70 and housing cover 14 would besnapped onto housing base 12.

[0024] FIGS. 2-6 will assist demonstrating precisely how rotationalmovement of mounting disc 18 results in appropriate linear movement offirst mounting pin 20 and second mounting pin 22 to selectively, butsecurely, attach alarm sensor 10 to corner walls 40 and 42. As seen inFIG. 2, rotatable mounting disc 18 includes optional directional arrows74 and 76 to instruct an installer in the direction rotatable mountingdisc 18 should be rotated to connect housing base 12 to walls 40 and 42.FIG. 2 demonstrates the position wherein rotatable mounting disc 18 hasalready been turned clockwise so that first mounting pin 20 and secondmounting pin 22 extend outwardly from housing base 12. Instead ofutilizing a screwdriver in screwdriver slot 62, it may be possible toutilize thumb turns 78 and 80 to rotate mounting disc 18.

[0025] In the preferred embodiment of the present invention, a mechanismhas been provided to prevent over-rotation of mounting disc 18 whichwould cause damage to first mounting pin 20 and second mounting pin 22.Referring to FIG. 4, it is shown that rotatable mounting disc 18includes a first protruding knob 82 and a second protruding knob 84.First protruding knob 82 travels along first guided groove 54 whereassecond protruding knob 84 travels along second guided groove 56. A firstnon-protruding engagement end 86 of first mounting pin 20 rests looselybetween first protruding knob 82 and a raised portion of mounting disc18. Similarly, a second non-protruding engagement end 88 of secondmounting pin 22 rests loosely between second protruding knob 84 and araised edge of mounting disc 18. First non-protruding engagement end 86and second non-protruding engagement end 88 preferably extend atapproximately 90° angles respectively from the rest of first mountingpin 20 and second mounting pin 22.

[0026]FIG. 4 shows the back of housing base 12 and mounting disc 18 in aposition wherein first mounting pin 20 and second mounting pin 22 areretracted within housing base 12. Conversely, FIG. 5 shows the back ofhousing base 12 and mounting disc 18 in a position wherein firstmounting pin 20 and second mounting pin 22 are extended beyond housingbase 12. This difference is caused by an approximately 45° turn ofmounting disc 18 from the inside of housing base 12. As shown in FIG. 4and FIG. 5, mounting disc 18 has been connected to housing base 12 bypressure mounting tabs 90, 92, 94 and 96. While experimentation hasshown that mounting disc 18 is most securely attached to housing base 12by utilizing four pressure mounting tabs, it is also possible to use twopressure mounting tabs. The utilization of pressure mounting tabs ispreferred since, should mounting disc 18 break it is easy to attach anew one to the existing housing base without replacing the entirehousing unit. However, there are many alternative techniques ofconnecting mounting disc 18 to housing base 12 that will become apparentto those skilled in the art.

[0027]FIG. 6 is a cross-sectional view of FIG. 5 taken along referenceline 6-6 and effectively shows the different components and shapes ofcomponents utilized in the preferred embodiment of the presentinvention. Of significant importance in the preferred embodiment is thefact that not only can housing base 12 be easily installed to cornerwalls 40 and 42, but, should the installer have made an error, thedevice is as easily removable and reinstalled at a new position. Thepins are sufficiently narrow so as to cause only negligible damage toany wall. Whether rotating mounting disc 18 to either retract or extendfirst mounting pin 20 and second mounting pin 22, first guided groove 54and second guided groove 56 prevent over-rotation of mounting disc 18 inany direction. Thus, any potential damage to first mounting pin 20 andsecond mounting pin 22 is eliminated.

[0028] Although, through experimentation, the rotation of mounting disc18 has been shown to be the best mode for achieving selective linearmovement of first mounting pin 20 and second mounting pin 22 from afirst retracted position to a second extended position, the utilizationof other means is also foreseen. For instance, the mounting pins can beselectively moved by means of a thumb-controlled, ratcheted devicesimilar to a smaller version of a car jack, by a geared wheel-turn, by alocked collar apparatus, or by other means known in the art for applyingsufficient and selective torque to the mounting pins. The various meansfor achieving selective, linear movement of the mounting pins should besufficiently small so as not to interfere with the replacement of theprinted circuit board on the housing base.

[0029] It will be apparent from the foregoing description that thepresent invention provides a new and improved method and apparatus forproviding an easy connection of an alarm sensor to the corner of a roomwith minimal risk to the circuitry and without utilizing of any screws,nails or mounting brackets. While a specific preferred embodiment hasbeen described, many variations may be utilized. For instance, althoughboth first mounting pin 20 and second mounting pin 22 have been shown toincorporate only a single prong, double pronged pins (similar tostaples) can be incorporated. Additionally, first mounting pin 20 andsecond mounting pin 22 can be threaded pins in certain variations.Moreover, while rotatable mounting disc 18 has been shown as beinggenerally circular and of a composite material, it can indeed takevarious shapes as long as its rotational movement will result in basiclinear movement of first mounting pin 20 and second mounting pin 22.

[0030] While there has been shown and described what is presentlyconsidered to be the preferred embodiment of this invention, it will beobvious to those skilled in the art that various changes andmodifications may be made without departing from the broader aspects ofthis invention. For instance, the preferred embodiment has described asingle rotatable mounting disc 18, which upon proper manipulation,simultaneously moves both first mounting pin 20 and second mounting pin22. It is certainly foreseen that separate mounting discs could beutilized for each mounting pin, particularly if the device is wide.Moreover, while a particular means for separating the housing base fromthe housing cover and the printed circuit board from the housing basehas been shown, many variations exist in the art.

[0031] It is, therefore, aimed in the appended claims to cover all suchchanges and modifications as fall within the true scope and spirit ofthe invention.

We claim:
 1. An alarm sensor for mounting between two corner wallscomprising: a housing unit having a housing base for attachment to saidcorner walls and a selectively detachable housing cover; a circuit boardsized for engagement within said housing unit; first and second openingson respectively opposing sides of said housing base; first and secondmounting pins selectively movable within said first and second openingsrespectively, said mounting pins having a length and a range of movementso as to create a first position wherein said mounting pins are totallyretracted within said housing unit and a second position wherein saidmounting pins extend outwardly from said housing unit sufficiently topierce said corner walls and securely hold said alarm sensor in place;and a rotatable mounting disc for selectively moving said first andsecond mounting pins between said first position and said secondposition.
 2. The alarm sensor of claim 1 wherein said mounting disc isrotatable by a screwdriver slot.
 3. The alarm sensor of claim 1 wherinsaid mounting disc is rotatable by a thumb turn.
 4. The alarm sensor ofclaim 1 wherein said mounting disc includes first and second protrudingknobs and said housing base includes respectively mating first andsecond guided grooves wherein said rotation of said mounting disc islimited by the length of said guided grooves.
 5. The alarm sensor ofclaim 4 wherein said first and second mounting pins each includenon-protruding engagement ends extending at an angle from said mountingpins wherein said non-protruding engagement ends extend between saidprotruding knobs and said mounting disc so that linear movement of saidfirst and second mounting pins is substantially limited to the samedistance as rotational movement of said mounting disc.
 6. The alarmsensor of claim 1 wherein said first and second mounting pins each haveprotruding ends which are pointed.
 7. The alarm sensor of claim 1wherein said first and second mounting pins each have protruding endswhich are double-pronged.
 8. The alarm sensor of claim 1 furthercomprising corner mount screw holes on said housing base.
 9. The alarmsensor of claim 1 further comprising flat wall mount screw holes on saidhousing base.
 10. The alarm sensor of claim 1 further comprising aswivel mount punch-out.
 11. The alarm sensor of claim 1 furthercomprising a wire entry punch-out.
 12. The alarm sensor of claim 1wherein said housing base includes a circuit board height index tab forselectively removing said circuit board from said housing unit.
 13. Thealarm sensor of claim 1 wherein said rotatable mounting disc is coupledto said housing base by at least two pressure mounting tabs.
 14. Amethod of securing a housing base of an alarm sensor having a rotatablemounting disc, and first and second opposing and selectively retractablemounting pins to a corner wall without screws comprising the steps of:holding said housing unit at a desired height on said corner walls; andturning said mounting disc so that said first and second mounting pinspierce said corner wall.
 15. The method of claim 14 wherein said turningstep is performed by hand.
 16. The method of claim 14 wherein saidturning step is performed by a screwdriver.
 17. An alarm sensor formounting on a wall comprising: a housing unit having a housing base forattachment to said wall and a selectively detachable housing cover; acircuit board sized for engagement within said housing unit; a firstopening on a side of said housing base; a first mounting pin selectivelymovable within said first opening, said first mounting pin having alength and a range of movement so as to create a first position whereinsaid first mounting pin is totally retracted within said housing unitand a second position wherein said first mounting pin extends outwardlyfrom said housing unit sufficiently to pierce said wall and securelyhold said alarm sensor in place; and a first rotatable mounting disc forselectively moving said first mounting pin between said first positionand said second position.
 18. The alarm sensor of claim 17 wherein saidfirst mounting disc is rotatable by a screwdriver slot.
 19. The alarmsensor of claim 17 wherein said first mounting disc is rotatable by athumb turn.
 20. The alarm sensor of claim 17 wherein said first mountingdisc includes a first protruding knob and said housing base includes amating first guided groove wherein said rotation of said first mountingdisc is limited by the length of said first guided groove.
 21. The alarmsensor of claim 20 wherein said first mounting pin includes a firstnon-protruding engagement end extending at an angle from said firstmounting pin wherein said first non-protruding engagement end extendsbetween said first protruding knob and said first mounting disc so thatlinear movement of said mounting pin is substantially limited to thesame distance as rotational movement of said first mounting disc. 22.The alarm sensor of claim 17 wherein said first mounting pin has aprotruding end which is pointed.
 23. The alarm sensor of claim 17wherein said first mounting pin has a protruding end which isdouble-pronged.
 24. The alarm sensor of claim 17 further comprisingcorner mount screw holes on said housing base.
 25. The alarm sensor ofclaim 17 further comprising flat wall mount screw holes on said housingbase.
 26. The alarm sensor of claim 17 further comprising a swivel mountpunch-out.
 27. The alarm sensor of claim 17 further comprising a wireentry punch-out.
 28. The alarm sensor of claim 17 wherein said housingbase includes a circuit board height index tab for selectively removingsaid circuit board from said housing unit.
 29. The alarm sensor of claim17 wherein said first rotatable mounting disc is coupled to said housingbase by at least two pressure mounting tabs.
 30. The alarm sensor ofclaim 17 further comprising: a second opening on a side of said housingbase opposite said first opening; a second mounting pin selectivelymovable within said second opening, said second mounting pin having alength and a range of movement so as to create a first position whereinsaid second mounting pin is totally retracted within said housing unitand a second position wherein said second mounting pin extends outwardlyfrom said housing unit sufficiently to pierce said wall and securelyhold said alarm sensor in place; and a second rotatable mounting discfor selectively moving said second mounting pin between said firstposition and said second position.
 31. The alarm sensor of claim 30wherein said second mounting disc is rotatable by a screwdriver slot.32. The alarm sensor of claim 30 wherein said second mounting disc isrotatable by a thumb turn.
 33. The alarm sensor of claim 30 wherein saidsecond mounting disc includes a second protruding knob and said housingbase includes a mating second guided groove wherein said rotation ofsaid mounting disc is limited by the length of said second guidedgroove.
 34. The alarm sensor of claim 33 wherein said second mountingpin includes a second non-protruding engagement end extending at anangle from said second mounting pin wherein said second non-protrudingengagement end extends between said second protruding knob and saidsecond mounting disc so that linear movement of said mounting pin issubstantially limited to the same distance as rotational movement ofsaid mounting disc.
 35. The alarm sensor of claim 30 wherein said secondmounting pin has a protruding end which is pointed.
 36. The alarm sensorof claim 30 wherein said second mounting pin has a protruding end whichis double-pronged.
 37. The alarm sensor of claim 30 wherein said secondrotatable mounting disc is coupled to said housing base by at least twopressure mounting tabs.
 38. A method of securing a housing base of analarm sensor having a rotatable mounting disc and a selectivelyretractable mounting pin to a corner wall without screws comprising thesteps of: holding said housing unit at a desired height on said cornerwall; and turning said mounting disc so that said mounting pin piercessaid corner wall.
 39. The method a claim 38 wherein said turning step isperformed by hand.
 40. The method of claim 38 wherein said turning stepis performed by a screwdriver.
 41. An alarm sensor for mounting betweentwo corner walls comprising: a housing unit having a housing base forattachment to said corner walls and a selectively detachable housingcover; a circuit board sized for engagement within said housing unit;first and second openings on respectively opposing sides of said housingbase; first and second mounting pins selectively movable within saidfirst and second openings respectively, said mounting pins having alength and a range of movement so as to create a first position whereinsaid mounting pins are totally retracted within said housing unit and asecond position wherein said mounting pins extend outwardly from saidhousing unit sufficiently to pierce said corner walls and securely holdsaid alarm sensor in place; and means coupled to said housing base forselectively moving said first and second mounting pins between saidfirst position and said second position.
 42. A method of securing ahousing base of an alarm sensor having first and second opposing andselectively retractable mounting pins, and means coupled to said housingbase for selectively moving said first and second mounting pins to acorner wall without screws comprising the steps of: holding said housingunit at a desired height on said corner walls; and manipulating saidmeans for selectively moving said first and second mounting pins so thatsaid first and second mounting pins pierce said corner wall.
 43. Analarm sensor for mounting on a wall comprising: a housing unit having ahousing base for attachment to said wall and a selectively detachablehousing cover; a circuit board sized for engagement within said housingunit; a first opening on a side of said housing base; a first mountingpin selectively movable within said first opening, said first mountingpin having a length and a range of movement so as to create a firstposition wherein said first mounting pin is totally retracted withinsaid housing unit and a second position wherein said first mounting pinextends outwardly from said housing unit sufficiently to pierce saidwall and securely hold said alarm sensor in place; and means coupled tosaid housing base for selectively moving said first mounting pin betweensaid first position and said second position.
 44. A method of securing ahousing base of an alarm sensor having a selectively retractablemounting pin and means coupled to said housing base for selectivelymoving said mounting pin without screws comprising the steps of: holdingsaid housing unit at a desired height on said corner wall; andmanipulating said means for selectively moving said mounting pin so thatsaid mounting pin pierces said corner wall.